2,227 research outputs found
Mudbricks, Construction Methods, and Stratigraphic Analysis : A Case Study at Tell Timai (ancient Thmuis) in the Egyptian Delta
The Graeco-Roman site of Tell Timai (ancient Thmuis) in Lower Egypt is among the largest urban tells in the Nile Delta, boasting substantial amounts of preserved earthen architecture. Although earthen architecture made up the vast majority of public and domestic structures in ancient Egypt, it still does not receive the same analytical attention from archaeologists as other categories of evidence. This paper presents a case study for the archaeological investigation of the earthen architecture at Tell Timai. The goal was to develop a methodology that can be implemented in the field by excavators with little geoarchaeological training and limited laboratory access in order to generate useful data for determining building stratigraphy and studying construction processes. Through the close examination and sampling of three buildings of different periods and scales, we tested a new field methodology combining geoarchaeological techniques and mensiochronology. The results provide information useful for stratigraphy and phasing as well as for identifying specific patterns of mudbrick manufacturing, production, and construction during the Graeco-Roman period at Tell Timai.Peer reviewe
B cell hyperresponsiveness and expansion of mature follicular B cells but not of marginal zone B cells in NFATc2/c3 double-deficient mice
Marginal zone (MZ) B cells and peritoneal B-I cells provide a first defense system of thymus-independent Ab responses against foreign pathogens and therefore share a number of functional properties. Recently, development of B-1a cells was shown to be controlled by the transcription factor NFATc1. We show here that mice deficient for NFATc2 and c3 display a distinct lower representation of MZ B cells, which is correlated with a reduced capturing of trinitrophenyl-Ficoll. In contrast, mature follicular B cells from NFATc2/c3(-/-) mice are strongly increased in number. NFATc2/c3-/- B cells exhibit a marked increase in BCR-induced intracellular Ca(2+) mobilization and proliferation. However, trinitrophenyl-Ficoll-specific IgM and IgG3 responses of NFATc2/c3-deficient mice are intact, and chimeric mice reconstituted with NFATc2/3-deficient B cells show a normal number of MZ B cells and normal BCR responses. These observations suggest that the strongly elevated Th2 cytokine milieu in NFATc2/c3-deficient mice leads to a hyperactivation of mature, follicular B cells, whereas MZ B cells are less responsive to these signals
Evolving Behavior Allocations in Robot Swarms
Behavioral diversity is known to benefit problem solving
in biological social systems such as insect colonies and human
societies, as well as in artificial distributed systems including
large-scale software and swarm-robotics systems. We investigate
methods of evolving robot swarms in which individuals have
heterogeneous behaviours. Two approaches are investigated to
create swarm of size n. The first encodes a repertoire of n
behaviours on a single individual, and hence evolves the swarm
directly. The second approach uses two phases. First, a large
repertoire of diverse behaviours is evolved and then another
evolutionary algorithm is used to search for an optimal allocation
of behaviours to the swarm. Results indicate that the two phase
approach of generate then allocate produces significantly more
effective collective behaviors (in terms of task accomplishment)
than the direct evolution of behaviorally heterogeneous swarms
Evolving Herding Behaviour Diversity in Robot Swarms
Behavioural diversity has been demonstrated as beneficial in biological
social systems, such as insect colonies and human societies,
as well as artificial systems such as large-scale software and
swarm-robotics systems. Evolutionary swarm robotics is a popular
experimental platform for demonstrating the emergence of
various social phenomena and collective behaviour, including behavioural
diversity and specialization. However, from an automated
design perspective, the evolutionary conditions necessary to synthesize
optimal collective behaviours (swarm-robotic controllers)
that function across increasingly complex environments (difficult
tasks), remains unclear. Thus, we introduce a comparative study
of behavioural-diversity maintenance methods (swarm-controller
extension of the MAP-Elites algorithm) versus those without behavioural
diversity mechanisms (Steady-State Genetic Algorithm),
as a means to evolve suitable degrees of behavioural diversity over
increasingly difficult collective behaviour (sheep-dog herding) tasks.
In support of previous work, experiment results demonstrate that
behavioural diversity can be generated without specific speciation
mechanisms or geographical isolation in the task environment, although
the direct evolution of a functionally (behaviorally) diverse
swarm does not yield high task performance
Tetramine Aspect Ratio and Flexibility Determine Framework Symmetry for Zn8L6 Self-Assembled Structures
We derive design principles for the assembly of rectangular tetramines into Zn8L6 pseudo-cubic coordination cages. Because of the rectangular, as opposed to square, geometry of the ligand panels, and the possibility of either Delta or ? handedness of each metal center at the eight corners of the pseudo-cube, many different cage diastereomers are possible. Each of the six tetra-aniline subcomponents investigated in this work assembled with zinc(II) and 2-formylpyridine in acetonitrile into a single Zn8L6 pseudo-cube diastereomer, however. Each product corresponded to one of four diastereomeric configurations, with T, T-h, S-6 or D-3 symmetry. The preferred diastereomer for a given tetra-aniline subcomponent was shown to be dependent on its aspect ratio and conformational flexibility. Analysis of computationally modeled individual faces or whole pseudo-cubes provided insight as to why the observed diastereomers were favored
Recommended from our members
Sterics and Hydrogen Bonding Control Stereochemistry and Self-Sorting in BINOL-Based Assemblies.
Here we demonstrate how the hydrogen-bonding ability of a BINOL-based dialdehyde subcomponent dictated the stereochemical outcome of its subsequent self-assembly into one diastereomeric helicate form when bearing free hydroxy groups, and another in the case of its methylated congener. The presence of methyl groups also altered the self-sorting behavior when mixed with another, short linear dialdehyde subcomponent, switching the outcome of the system from narcissistic to integrative self-sorting. In all cases, the axial chirality of the BINOL building block also dictated helicate metal center handedness during stereospecific self-assembly. A new family of stereochemically pure heteroleptic helicates were thus prepared using the new knowledge gained. We also found that switching from FeII to ZnII, or the incorporation of a longer linear ligand, favored heteroleptic structure formation
Sterics and Hydrogen Bonding Control Stereochemistry and Self-Sorting in BINOL-Based Assemblies
Here we demonstrate how the hydrogen-bonding ability of a BINOL-based dialdehyde subcomponent dictated the stereochemical outcome of its subsequent self-assembly into one diastereomeric helicate form when bearing free hydroxy groups, and another in the case of its methylated congener. The presence of methyl groups also altered the self-sorting behavior when mixed with another, short linear dialdehyde subcomponent, switching the outcome of the system from narcissistic to integrative self-sorting. In all cases, the axial chirality of the BINOL building block also dictated helicate metal center handedness during stereospecific self-assembly. A new family of stereochemically pure heteroleptic helicates were thus prepared using the new knowledge gained. We also found that switching from FeII to ZnII, or the incorporation of a longer linear ligand, favored heteroleptic structure formation
Efficiently Coevolving Deep Neural Networks and Data Augmentations
Designing large deep learning neural networks by
hand requires tuning large sets of method parameters, requiring
trial and error testing and domain specific knowledge. Neuroevolution methods such as CoDeepNeat (CDN), based on Neuroevolution of Augmenting Topologies (NEAT), apply evolutionary
algorithms to automate deep neural network parameter optimisation. This paper presents and demonstrates various novel
beneficial extensions to the CDN method, including new genotypic
speciation mechanisms, special mappings in deep neural network
encodings, as well as evolving Data Augmentation schemes.
Results indicate that these CDN method variants yield significant
task-performance benefits over the benchmark CDN method
when evaluated on a popular public image recognition data-set
- …